Intraluminal delivery of tissue lysing medium

ABSTRACT

A method and system for lysing a patient&#39;s heart tissue causing or involved with arrhythmia which includes an intravascular catheter with a relatively inelastic occlusion balloon on the distal end of the catheter which is inflated to block an artery or vein of the patient&#39;s heart so than when lysing fluid such as an ethanol solution is discharged from the distal port in the catheter the inflated balloon prevents the proximal refluxing of lysing medium into undesirable areas of the patient&#39;s heart. The inelastic balloon is configured to be inflated to a diameter of about 0.7 to about 1.3, preferably about 0.8 to about 1.2, times the diameter of the blood vessel in which the balloon is to be inflated so as to effectively occlude the passageway without damaging the wall of the blood vessel. The working length of the balloon is less than about 1.5 cm, preferably less than 0.75 cm.

BACKGROUND OF THE INVENTION

This application is directed to the treatment of arrhythmia andparticularly to the ablation of ectopic foci causing arrhythmia.

One method which has been used for treating arrhythmic conditions withina patient's heart involves the use of antiarrhythmic drugs such assodium and calcium channel blockers or drugs which reduce theBeta-adrenergic activity. Another method includes surgically sectioningthe origin of the signals causing the arrhythmia or a conducting pathwayfor such signals. Another frequently used method to terminate anarrhythmia is to destroy the heart tissue at the site from which thesignals causing the arrhythmia originate or tissue in a pathway throughwhich such signals pass. The methods used for destroying heart tissueinclude applying laser, radio frequency (RF) energy or microwave energyto the patient's endocardium at or close to the site from within thepatient's left or right ventricle in order to destroy heart tissueinvolved with the arrhythmia and thereby terminate the irregularheartbeat. The average arrhythmogenic site consists of a projected areaof about 1.4 cm² of endocardial tissue, and a re-entrant site might bemuch larger. Unfortunately, presently used RF ablation techniquesproduce lesions about 0.5 cm² in diameter, so a number of lesionsusually must be generated in order to effectively ablate an area ofinterest sufficiently to terminate the arrhythmia. If the site is notaccurately mapped or if there is difficulty in accurately placing and/orholding the distal tip of the ablation device, good tissue surroundingthe site which is neither the cause of nor involved with the arrhythmiawill be unnecessarily destroyed.

Prior ablation methods typically used elongated intravascular deviceswith distal portions disposed within a chamber of the patient's heartwhich have ablating means such as an RF emitting electrode or a laserdelivering optical fiber held in contact with the desired region of thepatient's endocardium to be destroyed. While this procedure is nowwidely practiced, precise positioning of the distal ablation portion ofthe intravascular device at the desired location where the tissuecausing or involved with the arrhythmia is to be destroyed remains aformidable problem.

Another method for terminating arrhythmia which has been experimentallyused is the chemical ablation of the region of the patient's heart fromwhich the irregular electrical activity originates, such as described byBrugada et al. in "Transcoronary Chemical Ablation of VentricularTachycardia", Circulation (1989); 79:475-482. In this procedure, icedsaline is first directed through a coronary artery which is believed todeliver blood to the ectopic foci or arrhythmogenic site. If thearrhythmia is temporarily terminated by the iced saline indicating thatthe arterial vessel feeds the origination site, then an aqueous solutionof ethanol is delivered through the arterial passageway to lyse thetissue at the origination site and permanently terminate the electricalactivity of such tissue. The alcohol solution quickly occludes thearterial passageway at the location into which it is introduced causinga myocardial infarct in the arrhythmogenic region of the patient'sheart. Unfortunately, the ethanol solution frequently refluxes to otherregions of the patient's heart, making this procedure very difficult tocontrol to a small region of the patient's myocardium. The region ofresulting tissue damage can be much larger than necessary to merelyterminate the arrhythmia. Due to the extensive risk of extraneous damageto the patient's myocardium from chemical ablation, this procedure hasnot been used except in limited experimental trials. See also Haines etal. in "Intracoronary Ethanol Ablation In Swine", J. of CardiovascularElectrophysiology, (1994); 5, No. 1, 41-49 and de Paola et al. in"Transcoroanry Chemical Ablation of Ventricular Tachycardia in ChronicChagasic Myocarditis", J. of the Ameican College of Cardiology, (1994);20, No. 2, 480-482.

What has been needed and heretofore unavailable is a method and systemfor lysing tissue at a site which causes or is involved with thearrhythmia but which does not destroy an excessive amount of uninvolvedtissue. The present invention satisfies these and other needs.

SUMMARY OF THE INVENTION

This invention is directed to a system for the delivery of lysing mediumto ablate tissue which either causes arrhythmia or is involved with theconductance of signals which result in arrhythmia.

The system of the invention includes an intravascular catheter which hasan elongated shaft with proximal and distal ends, a guidewire port inthe distal end, a first inner lumen which extends through at least aportion of the shaft to the port in the distal end of the shaft, asecond inner lumen which extends through a portion of the shaft to alocation spaced proximally from the distal end of the shaft and aninelastic inflatable member disposed on a distal portion of the shaft.The first inner lumen is configured to slidably receive a guiding memberto facilitate the advancement of the intravascular device through thepatient's vasculature. The inelastic inflatable member has a nominalworking diameter, i.e. in an inflated condition, of at least about 0.7to not more than about 1.3 times, preferably about 0.8 to about 1.2times, the diameter of the blood vessel in which the balloon is to beinflated. The balloon has a working length less than about 1.5 cm, andpreferably less than about 0.75 cm. As used herein the term inelasticrefers to having an elasticity of less than 10% at maximum workingpressure. As is recognized by those skilled in the art, blood vessels donot always have circular cross-section, and in those instances, thediameter is an averaged figure based upon the maximum and minimumcross-sectional dimensions.

The inner diameter of the vascular passageway in fluid communicationwith the tissue to be ablated is first determined to allow the selectionand use of an intravascular catheter with an appropriately sizedocclusion balloon.

An intravascular catheter of the invention with an appropriately sizedballoon is then advanced over an elongated guiding device such as aconventional guidewire to the desired location within the blood vessel,an artery which is believed to direct blood to the tissue at thearrhythmogenic or re-entry site or a vein which is believed to drainblood from such sites. With the occlusion balloon on the catheter in theblood vessel at the location in which the diameter of passageway hasbeen previously determined, the balloon is inflated to a diameter whichoccludes the passageway of the blood vessel. Tissue lysing media, suchas a 96% (by vol.) ethanol solution, is passed through the first innerlumen, out the distal port of the catheter and into the passageway ofthe blood vessel. The tissue distal to the catheter involved with thearrhythmia is lysed by contact with the ethanol and, additionally, thevascular passageway quickly becomes inflamed when contacted withethanol, occluding the passageway and preventing the passage ofoxygenated blood which thereby ensures that tissue cells are lysed.

The inflated balloon of the catheter blocks the passageway of the bloodvessel and prevents any proximal reflux of the ethanol or other lysingfluid into other regions of the patient's heart where such fluid candetrimentally effect good tissue not involved with the arrhythmia. Theinflated balloon also prevents the flow of substantial amounts of bloodthrough the passageway which might dilute the ethanol or other lysingfluid and reduce the effectiveness thereof. However, the balloon issufficiently short to prevent blocking branch arteries leading toregions of the patient's heart which is not involved with thearrhythmia.

In order to ensure that the passageway is in fluid communication withtissue causing or involved with the arrhythmia, iced saline solution isadvanced through the second inner lumen of the catheter to discharge thecold fluid into the blood vessel before lysing medium is delivered. Thelow temperature of the saline solution temporarily paralyzes the hearttissue to which the passageway of the blood vessel leads. If thearrhythmic conditions are terminated by such treatment, then thephysician will have reason to believe that the delivery of lysing fluidwill contact tissue involved with the arrhythmia and also permanentocclude the arterial passageway and thus will effectively treat thearrhythmia. The balloon on the catheter should be inflated when the icedsaline is delivered to prevent proximal reflux of the iced solutionwhich might lead to erroneous indications.

A key requirement for the success of the treatment is to preciselylocate the tissue causing or involved with the arrhythmia in order tolyse only a very small region of heart containing such tissue. Onepresently preferred method of locating the tissue causing or otherwiseinvolved with the arrhythmia is by means of an elongated intravasculardevice for detecting electrical activity within a patient's heart asdescribed in copending application Ser. No. 08/010,818, filed on Jan.29, 1993, now abandoned, application Ser. No. 08/043,449, filed Apr. 5,1993, now abandoned, application Ser. No. 08/057,294, filed May 5, 1993,now abandoned, and application Ser. No. 08/188,619, filed Jan. 27, 1994,now U.S. Pat. No. 5,509,411, which are incorporated herein in theirentireties by reference. The devices described in these references havea plurality of sensing electrodes on a distal portion thereof and areadvanced within the patient's coronary arteries or cardiac veins so thatelectrical activity can be detected at various locations within thepatient's heart and the sensed electrical activity may then be used tofind the intravascular location close to the arrhythmogenic or re-entrysite. Once such a site is located, the catheter of the invention can beemployed to lyse the tissue at the site. The intravascular device usedto detect the electrical activity may also be used to guide the catheterto the site as would a guidewire. When the arrhythmogenic or re-entrysite is located, the intravascular device can be left in place, thecatheter advanced over the device until the balloon on the catheter ispositioned at the desired location where it is inflated and lysingmedium delivered to the desire location distal to the occluding balloonon the catheter.

These and other advantages of the invention will become more apparentfrom the following detailed description thereof when taken inconjunction with the accompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view, partially in section, of a catheterassembly embodying features of the invention.

FIG. 2 is a transverse cross-sectional view of the assembly shown inFIG. 1, taken along the lines 2--2.

FIG. 3 is an enlarged view of the distal end of the catheter assemblywithin a patient's artery with the balloon in an inflated condition toocclude the artery.

FIG. 3A is an enlarged view of the distal end of the catheter assemblywithin a patient's vein with the balloon in an inflated condition toocclude the vein.

FIG. 4 is an elevational view, partially in section, of aelectrophysiology device which may be utilized to detect arrhythmogenicsites.

FIG. 5 is a longitudinal cross-sectional view of the distal portion ofthe electrophysiology member shown in FIG. 4

FIG. 6 is a longitudinal cross-sectional view of the electrophysiologymember shown in FIG. 4 taken along the lines 6--6.

FIG. 7 is a transverse cross-sectional view of the electrophysiologymember shown in FIG. 4 taken along the lines 7--7.

FIG. 8 is a longitudinal cross-sectional view of the proximal portion ofthe electrophysiology member shown in FIG. 4 taken along the lines 8--8.

DETAILED DESCRIPTION OF THE INVENTION

As depicted in FIGS. 1-3, the catheter assembly of a presently preferredembodiment of the invention includes a catheter 10 and a guiding member11, e.g. a guidewire, over which the catheter is advanced within apatient's vascular system. The catheter 10 has a shaft 12 with a distalportion 13, a proximal portion 14 and an adapter 15 on the proximal endof the catheter shaft. The catheter shaft 12 has a first inner lumen 16configured to slidably receive the elongated guiding member 11 whichextends from the proximal end of the shaft 12 to port 17 in the distalend of the catheter shaft and a second inner lumen 18 which extends fromthe proximal end to a location proximal to the distal end of thecatheter shaft. An inelastic balloon 20, formed of polyethyleneterephthalate (PET), polyethylene, polyolefins and the like, is providedon the distal portion 13 which has an interior in fluid communicationwith the second inner lumen 18. The working length of the balloon 20 isindicated by L.

The adapter 15 on the proximal end of the catheter shaft 12 has a sidearm 21 which is in fluid communication with second inner lumen 18 and acentral arm 22 which is in fluid communication with the first innerlumen 16.

The guiding member 11 may be a conventional guidewire as depicted inFIGS. 1-3 with a core member 25, a tapered distal section 26 disposedwithin helical coil 27. The distal end of the coil 27 is secured to thedistal end of the tapered distal section 26 by means of solder, brazing,welding and the like to form the rounded plug 28. The proximal end ofthe coil 27 is secured in a similar manner to the core member 25 at aproximal location 29. The distal portion of the tapered section 26 istypically flatted into a rectangular transverse cross-section to provideincreased flexibility in one direction.

In FIG. 3, the catheter 10 is shown disposed within an arterialpassageway 30 with the balloon 20 in an inflated condition to itsworking diameter so as to occlude the passageway. Preferably, theinflated balloon 20 contacts and slightly expands the artery wall 31. Abody of blood 32 is disposed within the arterial passageway 30 proximalto the balloon 20 resulting from the occlusion by the inflated balloonand lysing medium 33 is discharged from the distal end of the catheter10 through port 17 into passageway 30 distal to the balloon. The lysingmedium is introduced into the first inner lumen 16 of catheter 10through the center arm 21 of adapter 15. A suitable lysing medium is asolution of ethanol (e.g. 50% by vol. or greater). Another suitablelysing media which may be used in phenol. As is recognized by thoseskilled in the art a variety of lysing agents may be employed, eitheralone or in mixtures thereof. A radiopaque marker 34 is provided on theshaft distal to the balloon 20 to facilitate fluoroscopic determinationof balloon location during the procedure.

In FIG. 3A, the blood vessel shown is a cardiac vein 35 with a body 36of venous blood distal to the inflated balloon 20 within the venouspassageway 37. The reference numbers used in this figure are otherwisethe same as in FIG. 3

An electrophysiological device 40, as illustrated in FIGS. 4-7, may beused to detect electrical activity causing or involved with thearrhythmia from within the patient's coronary arteries or cardiac veins.This device is described and claimed in copending application Ser. No.08/188,619, filed on Jan. 27, 1994, and which has been incorporatedherein by reference. In this embodiment, the electrophysiological device40 has a plurality of sensing electrodes 41 disposed on the distalportion 42 in pairs 43 for bipolar mode detection of electricalactivity. Details of the distal portion 42 are shown in FIGS. 5 and 7.The shaft 44 is formed of a braided tubular member 45 formed of aplurality of electrical conductors 46. The insulation on separateconductors 46 is exposed under each of the sensing electrodes 41 so thatan electrical connection can be made between the electrodes and theelectrical conductors. The electrical connection may be secured by meansof a suitable solder or brazing material, or by resistance welding, andthe electrodes may also be secured to the underlying tubular member by asuitable means such as an adhesive to ensure maintenance of electricalcontact with the exposed conductors. All of the strands of the braidedtubular member 45 need not be conductors and may be formed of polymermaterials such as nylon. A polymer jacket 47 is disposed about thebraided tubular member 45 to provide a smoother exterior surface to thedevice. Suitable polymer materials for the jacket 47 include a highdensity polyethylene, a thermoplastic polyurethane, polyvinyl chloride,a polyolefinic ionamers such as Surlyn®. Other polymers may also beemployed.

A core member 50 is disposed within the inner lumen of the braidedtubular member 45 and extends beyond the distal end thereof. A distalcoil 51 is disposed about and secured by suitable means, such asbrazing, soldering or an appropriate adhesive, to the distal extremityof the core member 50 and is provided with a smooth rounded distal tip52 formed by joining the distal tip of the coil 51 to the distalextremity of the core member 50. The core 50 may be formed of suitablemetallic materials such as stainless steel. Other materials arecontemplated.

The proximal section 53 of the device 40 as shown in FIG. 4 has twoextensions 54 and 55 which have multi-pin connectors 56 and 57 on theproximal ends thereof. Details of the connector 56 is depicted in FIG.8. While not shown, each of the electrical conductors 46 areelectrically connected to a separate pin 58. A sixteen pin connector isschematically shown in FIG. 8 but connectors having a higher or lowernumber of pins may be suitable. The electrical conductors 46 are bundledtogether within the center of the extension.

The electrophysiology device 40 may be used independently of theoccluding catheter 10, in which case the device is advanced through thepatient's blood vessel to several locations therein to detect electricalactivity and from this electrical activity determine the vascularlocation close to the origination or pathway tissue. The location isnoted and the device 40 may then be removed. The device 40 can beadvanced through the venous side such as through the patients coronarysinus into the great cardiac vein or other veins which lead to thecoronary sinus and the great vein or it can be advanced through thepatient's coronary arteries. Once the electrophysiology device isremoved, the guidewire 11 and catheter 10 as shown in FIGS. 1 and 2 canbe advanced into the veins or arteries of the patient's heart in aconventional manner until the occluding balloon 20 of the catheter 10 isdisposed within a blood vessel (artery or vein) at a location in whichthe inner diameter thereof has been determined and which is in closeproximity to and in fluid communication with the tissue involved withthe arrhythmia. The occluding balloon 20 may then be inflated to theapproximate inner diameter of the blood vessel at the selected locationand the lysing medium discharged from the port 17 of the catheter 10 asdescribed above. As previously described, the iced saline may be firstdischarged to paralyze the tissue distal to the catheter. If thearrhythmia is terminated by the delivery of the iced saline, thephysician is reasonably assured that the arrhythmia will be permanentlyterminated by the delivery of the lysing medium to the same location.

In another method, the electrophysiology device 40 is used as aguidewire where the catheter is slidably mounted onto the device 40before it is introduced into the patient's vasculature. Both the device40 and the catheter 10 are then advanced through the vasculature withthe distal portion 42 of the device extending out the distal end of thecatheter 10 so as to detect electrical activity involved with thearrhythmia. When the arrhythmogenic site or pathway is located, thecatheter 10 can then be suitably advanced over the device 40 until theballoon 20 is disposed in a vascular location in fluid communicationwith the arrhythmogenic or pathway tissue. Inflation of the balloonoccludes the vascular passageway 30 and lysing medium can be dischargedfrom the distal port 17 to lyse tissue involve with the arrhythmia. Inthis instance the electrophysiology device 40 is longer than thecatheter 10 and is preferably about 25 to about 75 cm longer than thecatheter.

While the present invention is described herein in terms of certainpreferred embodiments, those skilled in the art will recognize thatvarious modifications and improvements can be made to the inventionwithout departing from the scope thereof.

What is claimed is:
 1. An occluding intravascular catheter for deliveryof lysing medium to a blood vessel within a patient's heart having apredetermined inner diameter, comprising:a) an elongated shaft havingproximal and distal ends, a port in the distal end, a first inner lumenextending within the catheter shaft to the port in the distal end, asecond inner lumen extending within the shaft to a location proximal tothe distal end; and b) an inflatable member on a distal portion of thecatheter shaft having an interior in fluid communication with the secondinner lumen and having a maximum inflated diameter between about 0.7 toabout 1.3 times the predetermined inner diameter of the patient's bloodvessel.
 2. The intravascular catheter of claim 1 wherein the inflatablemember has a working length of less than 1.5 cm.
 3. The intravascularcatheter of claim 1 wherein the inflatable member has a working lengthof less than about 0.75 cm.
 4. The intravascular catheter of claim 1wherein the maximum inflated diameter of the inflatable member is about0.8 to about 1.2 times the inner diameter of the patient's blood vessel.5. A method for treating a patient's heart exhibiting arrhythmia,comprising:a) determining the transverse dimensions of a blood vessel ata desired location within the patient's heart in fluid communicationwith heart tissue involved with the patient's arrhythmia; b) providing acatheter comprisinga catheter shaft which has proximal and distal ends,a port in the distal end of the catheter, a first inner lumen extendingwithin the catheter shaft to the port in the distal end, a second innerlumen extending within the catheter shaft to a location proximal to thedistal end of the catheter shaft, an occlusion balloon on a distalportion of the catheter shaft which has a maximum inflated diameter ofabout 0.7 to about 1.3 times an average transverse inner dimension ofthe arterial passageway and which has an interior in fluid communicationwith the second inner lumen; e) advancing the catheter within thepatient's vasculature until the occluding balloon on the distal portionof the catheter shaft is disposed within the blood vessel at thelocation in which the inner diameter has been determined; f) inflatingthe occlusion balloon to a diameter of about 0.7 to about 1.3 times theinner dimensions of the blood vessel to occlude the blood vessel; and g)directing lysing medium through the first inner lumen of the catheter,out the port in the distal end thereof into the blood vessel to thedesired location within the blood vessel distal to the catheter to lysetissue causing or involved with the arrhythmia, while the balloonoccludes the blood vessel to prevent the proximal refluxing of lysingmedium to undesirable locations within the patient's heart.
 6. Themethod of claim 5 wherein the balloon is inflated to a diameter of about0.8 to about 1.2 times an average inner dimension of the blood vessel.7. A method for treating a patient experiencing arrhythmia,comprising:a) advancing at least one intravascular guidewire having aplurality of sensing electrodes on a distal portion thereof through thepatient's coronary arterial system; b) detecting electrical activityfrom heart tissue to locate heart tissue causing or involved with thearrhythmia; c) determining an average inner dimension of a coronaryartery which is in fluid communication with heart tissue causing orinvolved with the arrhythmia; d) providing a catheter comprisingacatheter shaft which has proximal and distal ends, a port in the distalend of the catheter, a first inner lumen extending within the cathetershaft to the port in the distal end, a second inner lumen extendingwithin the catheter shaft to a location proximal to the distal end ofthe catheter shaft, a relatively short occlusion balloon on a distalportion of the catheter shaft which has a maximum inflated diameter ofbetween about 0.7 to about 1.3 of the determined inner diameter of thecoronary artery and which has an interior in fluid communication withthe second inner lumen; e) advancing the catheter over the guidewirewith the guidewire slidably disposed within the first inner lumen untilthe balloon on the distal portion of the catheter shaft is located at adesired location within the patient's coronary artery; f) passinginflation fluid through the second inner lumen into the interior of theballoon to inflate the balloon until the diameter of the inflatedballoon is about 0.7 to about 1.3 times the determined inner diameter ofthe coronary artery at a desired location so as to occlude the arterialpassageway thereof sufficiently to prevent the proximal passage ofsignificant quantities of lysing medium by the inflated balloon; and g)directing lysing medium through the first inner lumen of the catheterand out the port in the distal end thereof while the balloon is inflatedto deliver said lysing medium to the desired location within thecoronary artery distal to the catheter to lyse tissue causing orinvolved with arrhythmia.
 8. The method of claim 7 wherein the balloonis inflated to a diameter of about 0.9 to about 1.1 times the determineddiameter of the coronary artery.